Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Pretty soon, heat pumps will be able to store and distribute heat as needed

sintef.no

Post reply on HN
Print view View original

111–120 of 243 posts

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#111

Post by thescriptkiddie »

5ersi wrote: post #109

It uses phase change (solid to liquid) to store heat at about 200 kJ/kg. Compare this to heating water in a boiler from 10c to 60c - stores 209 kJ/kg. So we already have an effective way to store heat which can work for decades without servicing and is also cheap to produce (in terms of money and energy consumption).

one difference is that a phase change stores energy at constant temperature, which may be desirable given that heat pump efficiency is inversely proportional to temperature output temperature

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#112

Post by bethekidyouwant »

wffurr wrote: post #110
AlexandrB wrote: post #82

Earlier quoted context omitted.

But dumping the waste cold air into the house when it's below 0C outside doesn't make much sense either.

You already dump waste hot air into your kitchen from the refrigerator during the summer. Is this much different? It does seem a little silly to have these chains of heat pumps all working in various directions. I read about "cold district heat" in a sibling comment which circulated lukewarm water to use as a heat sink or source with heat pumps. Maybe something similar could be done with a water or refrigerant loop t…

A hot water heater takes much more power than a fridge

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#113

Post by hedora »

karussell wrote: post #96
hedora wrote: post #10

I wonder if this can store any heat or just heat pump heat. If it can store any heat, it would help a lot to further reduce heating costs in our modern energy efficient house. Sometimes, in the winter, we get too much solar forcing, so if we don’t heat all, it can be 85F in the day in the house, but 60-65 at night. (We open the windows during the day, and don’t always close them at exactly the right time at night.)

I think this can work and instead of that the heatpump pumps the heat into your house (when "solar is plenty") it would pump it into the storage. (I have a similar setup, but heat the water but of course this is rather limited) unrelated: a simple technical solution to your window problem would be home assistant and a few sensors to notify you when the windows are open too long or open when too cold inside.

It’s more about predictive modeling: At what time + temperature do you close windows, given predicted cloud cover and overnight temperatures/wind?

Come to think of it, if we had a big salt slurry that transitioned at 72F in the floors, that would probably do the right thing. It’d create a step function making it hard to heat above 72, or cool below it.

I wonder how much density changes as these things transition. Would a static pool (mixed by freezing) work, or would it need a pump?

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#114

Post by yowayb »

ortusdux wrote: post #83

I was interested to learn about cold district heating recently, which is basically a municipal scale geothermal system. https://en.wikipedia.org/wiki/Cold_district_heating

I went to Moscow in December several years ago and learned they've got one the world's largest district heating systems.

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#115

Post by LoganDark »

Loughla wrote: post #97
chankstein38 wrote: post #57

They should've used lasagna. You could be in a tundra heating it over a fire and, as long as you get it sufficiently and consistently hot, it'll still burn your mouth 20minutes later.

And yet, if you make it like I do, there always manages to be one piece that is ice cold while the rest is shockingly hot. Even if you're start with warm ingredients. Physics does not apply to lasagna. Also I suck at making lasagna.

I don't know how you cook your lasagna, but cooking for longer at a lower temperature usually results in more even heating than cooking for less long at a higher temperature. (This is one of the reasons microwaves are so terrible at heating evenly.) If you're not already, that may help.

(I also imagine using the circulation in a convection oven might help as well. Also, preheating your oven! Even if it's a toaster oven.)

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#116

Post by lm28469 »

wffurr wrote: post #110
AlexandrB wrote: post #82

Earlier quoted context omitted.

But dumping the waste cold air into the house when it's below 0C outside doesn't make much sense either.

You already dump waste hot air into your kitchen from the refrigerator during the summer. Is this much different? It does seem a little silly to have these chains of heat pumps all working in various directions. I read about "cold district heat" in a sibling comment which circulated lukewarm water to use as a heat sink or source with heat pumps. Maybe something similar could be done with a water or refrigerant loop t…

> you already dump waste hot air into your kitchen from the refrigerator during the summer. Is this much different?

Heating water is very energy intensive, fridges are a rounding error compared to water heaters

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#117

Post by esseph »

LoganDark wrote: post #115
Loughla wrote: post #97

Earlier quoted context omitted.

And yet, if you make it like I do, there always manages to be one piece that is ice cold while the rest is shockingly hot. Even if you're start with warm ingredients. Physics does not apply to lasagna. Also I suck at making lasagna.

I don't know how you cook your lasagna, but cooking for longer at a lower temperature usually results in more even heating than cooking for less long at a higher temperature. (This is one of the reasons microwaves are so terrible at heating evenly.) If you're not already, that may help. (I also imagine using the circulation in a convection oven might help as well. Also, preheating your oven! Even if it's a toaster ov…

Microwave tip:

Use the power button to select a lower power level, and cook the food for longer.

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#118

Post by newhotelowner »

jandrese wrote: post #62

I've been keeping an eye on heat pump water heaters for awhile, but right now they mostly make sense in warm climates. The big problem is they're still specialty products and marked up like crazy, but also they tend to use cheap components which makes them loud and prone to failure. If you run A/C for the majority of the year then they pay themselves back reasonably quick, barring early failure, but in colder climate…

They marketing like it's an expensive tech, but it's pretty cheap.

We have been buying heat pump PTAC for the hotels for last 20 years, and price difference is usually 5% between with and without heat pump.

Seems like all companies are colluding with each other for marking up prices.

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#119

Post by gpm »

belviewreview wrote: post #13
syntaxing wrote: post #7

With the adoption of sodium batteries, I wouldn’t be surprised if solar panel + sodium battery would outperform this system by a lot.

A heat pump gets more heat from a given amount of electricity than if the electricity is use for resistive heating. So the ideal design is solar cell + sodium battery + heat pump.

Also when the temperature differential is lower, so ideal might be solar -> battery (to time shift to warmest outdoor temperature) -> heat pump -> thermal battery (to time shift to when you need heat).

Does seem like a lot of added complexity (and likely machinery cost) though.

Re: Pretty soon, heat pumps will be able to store and distribute heat as needed

#120

Post by xattt »

yowayb wrote: post #114
ortusdux wrote: post #83

I was interested to learn about cold district heating recently, which is basically a municipal scale geothermal system. https://en.wikipedia.org/wiki/Cold_district_heating

I went to Moscow in December several years ago and learned they've got one the world's largest district heating systems.

I am not sure if this is still the case, but up to 20 years ago, these were typically shut off in May-June to August for “maintenance” which resulted in a prolonged period of no hot water in apartments.
Post reply on HN